fix: keep tab controls on split panes and the window draggable from the top

CHANGELOG.md

@@ -16,7 +16,7 @@ Programa is a fork of [cmux](https://github.com/manaflow-ai/cmux); for history p
 - On Windows, pasting text with line breaks or control characters into a program that has not turned on bracketed paste (cmd.exe, PowerShell) asks first, with a preview.
 
 ### Changed
-- A pane with a single tab hides its tab bar, along with the new-tab and split buttons. The bar comes back when the pane gets a second tab.
+- A workspace with a single tab hides its tab bar, along with the new-tab and split buttons, and leaves an empty strip in its place so the window can still be dragged from the top. A glass + button in that strip's right corner opens a new tab. The bar comes back when the pane gets a second tab or the workspace is split, so every split pane keeps its close and new-tab buttons.
 - A focused terminal that has nothing new to show uses about half as much CPU. It stops waking up on every screen refresh after a quarter second of quiet and starts again on the next change.
 - Only one copy of Programa runs at a time: launching a second copy brings the running app forward and exits.
 - Closing a window with its red button or Close Window asks first when any of its workspaces has a running process, with the same confirmation as closing the last workspace. The socket method `window.close` still closes without asking.

Sources/AppDelegate+UITestHarnesses.swift

@@ -152,6 +152,8 @@ extension AppDelegate {
         guard env["PROGRAMA_UI_TEST_BONSPLIT_TAB_DRAG_SETUP"] == "1" else { return }
         guard tabManager != nil else { return }
         let startWithHiddenSidebar = env["PROGRAMA_UI_TEST_BONSPLIT_START_WITH_HIDDEN_SIDEBAR"] == "1"
+        let splitPanes = env["PROGRAMA_UI_TEST_BONSPLIT_SPLIT_PANES"] == "1"
+        let singleTab = env["PROGRAMA_UI_TEST_BONSPLIT_SINGLE_TAB"] == "1"
 
         let deadline = Date().addingTimeInterval(20.0)
         func hasMainTerminalWindow() -> Bool {
@@ -204,7 +206,20 @@ extension AppDelegate {
             let betaTitle = "UITest Beta"
             tabManager.setCustomTitle(tabId: workspace.id, title: workspaceTitle)
             workspace.setPanelCustomTitle(panelId: alphaPanelId, title: alphaTitle)
-            tabManager.newSurface()
+            if singleTab {
+                self.writeBonsplitTabDragUITestData([
+                    "ready": "1",
+                    "workspaceId": workspace.id.uuidString,
+                    "alphaTitle": alphaTitle,
+                    "alphaPanelId": alphaPanelId.uuidString,
+                ])
+                return
+            }
+            if splitPanes {
+                tabManager.createSplit(direction: .right)
+            } else {
+                tabManager.newSurface()
+            }
 
             guard let betaPanelId = workspace.focusedPanelId, betaPanelId != alphaPanelId else {
                 self.writeBonsplitTabDragUITestData(["setupError": "Failed to create second surface"])

programaUITests/BonsplitTabDragUITests.swift

@@ -418,13 +418,86 @@ final class BonsplitTabDragUITests: XCTestCase {
         )
     }
 
+    func testSplitPanesWithOneTabEachKeepTheirTabBars() {
+        let (app, dataPath) = launchConfiguredApp(splitPanes: true)
+
+        XCTAssertTrue(
+            ensureForegroundAfterLaunch(app, timeout: launchTimeout),
+            "Expected app to launch for split-pane tab bar UI test. state=\(app.state.rawValue)"
+        )
+        XCTAssertTrue(waitForAnyJSON(atPath: dataPath, timeout: setupTimeout), "Expected tab-drag setup data at \(dataPath)")
+        guard let ready = waitForJSONKey("ready", equals: "1", atPath: dataPath, timeout: setupTimeout) else {
+            XCTFail("Timed out waiting for ready=1. data=\(loadJSON(atPath: dataPath) ?? [:])")
+            return
+        }
+
+        if let setupError = ready["setupError"], !setupError.isEmpty {
+            XCTFail("Setup failed: \(setupError)")
+            return
+        }
+
+        let window = app.windows.element(boundBy: 0)
+        XCTAssertTrue(window.waitForExistence(timeout: 5.0), "Expected main window to exist")
+
+        // Each pane holds a single tab. Its tab bar still has to show, since that bar
+        // carries the close and new-tab controls that undo the split. `isHittable` is
+        // not usable here: XCUI cannot hit-test through the macOS 26 glass tab pills.
+        let alphaTab = app.buttons[ready["alphaTitle"] ?? "UITest Alpha"]
+        let betaTab = app.buttons[ready["betaTitle"] ?? "UITest Beta"]
+        XCTAssertTrue(
+            waitForCondition(timeout: 5.0) { alphaTab.exists && window.frame.contains(alphaTab.frame) },
+            "Expected the left pane's tab bar to show its only tab. window=\(window.frame) alpha=\(alphaTab.debugDescription)"
+        )
+        XCTAssertTrue(
+            waitForCondition(timeout: 5.0) { betaTab.exists && window.frame.contains(betaTab.frame) },
+            "Expected the right pane's tab bar to show its only tab. window=\(window.frame) beta=\(betaTab.debugDescription)"
+        )
+        XCTAssertLessThan(alphaTab.frame.midX, betaTab.frame.midX, "Expected alpha and beta in side-by-side panes")
+    }
+
+    func testSingleTabFloatingNewTabButtonOpensATab() {
+        let (app, dataPath) = launchConfiguredApp(singleTab: true)
+
+        XCTAssertTrue(
+            ensureForegroundAfterLaunch(app, timeout: launchTimeout),
+            "Expected app to launch for floating new-tab button UI test. state=\(app.state.rawValue)"
+        )
+        XCTAssertTrue(waitForAnyJSON(atPath: dataPath, timeout: setupTimeout), "Expected tab-drag setup data at \(dataPath)")
+        guard let ready = waitForJSONKey("ready", equals: "1", atPath: dataPath, timeout: setupTimeout) else {
+            XCTFail("Timed out waiting for ready=1. data=\(loadJSON(atPath: dataPath) ?? [:])")
+            return
+        }
+        if let setupError = ready["setupError"], !setupError.isEmpty {
+            XCTFail("Setup failed: \(setupError)")
+            return
+        }
+
+        let window = app.windows.element(boundBy: 0)
+        XCTAssertTrue(window.waitForExistence(timeout: 5.0), "Expected main window to exist")
+
+        // A single tab hides its tab bar, so the strip left in its place carries the "+".
+        let alphaTab = app.buttons[ready["alphaTitle"] ?? "UITest Alpha"]
+        let newTabButton = app.descendants(matching: .any).matching(identifier: "paneFloatingNewTabButton").firstMatch
+        XCTAssertTrue(newTabButton.waitForExistence(timeout: 5.0), "Expected the floating new-tab button with a single tab")
+        XCTAssertFalse(alphaTab.exists, "Expected the single tab's tab bar to be hidden")
+
+        newTabButton.click()
+
+        XCTAssertTrue(
+            waitForCondition(timeout: 5.0) { alphaTab.exists && !newTabButton.exists },
+            "Expected the click to open a second tab and bring the tab bar back. alpha=\(alphaTab.debugDescription)"
+        )
+    }
+
     private enum WorkspacePresentationMode: String {
         case standard
         case minimal
     }
 
     private func launchConfiguredApp(
         startWithHiddenSidebar: Bool = false,
+        splitPanes: Bool = false,
+        singleTab: Bool = false,
         presentationMode: WorkspacePresentationMode = .minimal
     ) -> (XCUIApplication, String) {
         let app = XCUIApplication()
@@ -436,6 +509,12 @@ final class BonsplitTabDragUITests: XCTestCase {
         if startWithHiddenSidebar {
             app.launchEnvironment["PROGRAMA_UI_TEST_BONSPLIT_START_WITH_HIDDEN_SIDEBAR"] = "1"
         }
+        if splitPanes {
+            app.launchEnvironment["PROGRAMA_UI_TEST_BONSPLIT_SPLIT_PANES"] = "1"
+        }
+        if singleTab {
+            app.launchEnvironment["PROGRAMA_UI_TEST_BONSPLIT_SINGLE_TAB"] = "1"
+        }
         app.launchArguments += ["-workspacePresentationMode", presentationMode.rawValue]
         app.launch()
         app.activate()

vendor/bonsplit/Sources/Bonsplit/Internal/Views/PaneContainerView.swift

@@ -558,12 +558,14 @@ struct PaneContainerView<Content: View, EmptyContent: View>: View {
             : 0
     }
 
-    /// A pane with exactly one tab has nothing to switch between, so its strip is
-    /// hidden. A nonzero `leadingInset` means the strip doubles as the titlebar row
-    /// beside the traffic lights (minimal mode, sidebar hidden); it stays so the
-    /// terminal does not slide under them and the window remains draggable there.
+    /// The only pane of a workspace with exactly one tab has nothing to switch
+    /// between, so its strip is hidden and an empty drag band takes its place. Once the workspace is split, every pane keeps
+    /// its strip: it carries the close, new-tab and split controls that undo the split.
+    /// A nonzero `leadingInset` means the strip doubles as the titlebar row beside the
+    /// traffic lights (minimal mode, sidebar hidden); it stays so the terminal does not
+    /// slide under them and the window remains draggable there.
     private var showsTabStrip: Bool {
-        pane.tabs.count != 1 || leadingInset > 0
+        pane.tabs.count != 1 || leadingInset > 0 || controller.rootNode.allPaneIds.count > 1
     }
 
     var body: some View {
@@ -592,6 +594,23 @@ struct PaneContainerView<Content: View, EmptyContent: View>: View {
                     showSplitButtons: showSplitButtons
                 )
             }
+            if !showsTabStrip {
+                // The hidden strip's pane sits at the window top, so this band stands
+                // in for the titlebar: without it nothing up there drags the window.
+                TabBarDragZoneView()
+                    .frame(height: usesNativePaneChrome ? TabBarGlassStyling.barHeight : TabBarMetrics.barHeight)
+                    .accessibilityHidden(true)
+                    .overlay(alignment: .trailing) {
+                        FloatingNewTabButton(
+                            title: Bundle.module.localizedString(forKey: "tabBar.newTab", value: "New Tab", table: nil)
+                        ) { [weak pane, weak bonsplitController] in
+                            guard let pane, let bonsplitController else { return }
+                            bonsplitController.requestNewTab(kind: "terminal", inPane: pane.id)
+                        }
+                        .frame(width: 24, height: 22)
+                        .padding(.trailing, 8)
+                    }
+            }
 
             // Content area with drop zones
             contentAreaWithDropZones
@@ -1011,3 +1030,51 @@ struct UnifiedPaneDropDelegate: DropDelegate {
         return nil
     }
 }
+
+/// The "+" that opens a new tab from the empty strip a single tab leaves behind.
+/// It is an AppKit button on purpose: the window's titlebar-drag routing in
+/// `programa_sendEvent` turns a click on plain SwiftUI content there into a window drag.
+private struct FloatingNewTabButton: NSViewRepresentable {
+    let title: String
+    let action: () -> Void
+
+    func makeCoordinator() -> Coordinator { Coordinator(action: action) }
+
+    func makeNSView(context: Context) -> NSView {
+        let button = NSButton(frame: .zero)
+        button.image = NSImage(systemSymbolName: "plus", accessibilityDescription: title)
+        button.isBordered = false
+        button.contentTintColor = .secondaryLabelColor
+        button.toolTip = title
+        button.setAccessibilityLabel(title)
+        button.setAccessibilityIdentifier("paneFloatingNewTabButton")
+        button.target = context.coordinator
+        button.action = #selector(Coordinator.pressed)
+        #if compiler(>=6.2)
+        if #available(macOS 26.0, *) {
+            let glass = NSGlassEffectView(frame: .zero)
+            glass.style = .regular
+            glass.cornerRadius = 11
+            glass.contentView = button
+            return glass
+        }
+        #endif
+        return button
+    }
+
+    func updateNSView(_ nsView: NSView, context: Context) {
+        context.coordinator.action = action
+    }
+
+    final class Coordinator: NSObject {
+        var action: () -> Void
+
+        init(action: @escaping () -> Void) {
+            self.action = action
+        }
+
+        @objc func pressed() {
+            action()
+        }
+    }
+}

vendor/bonsplit/Sources/Bonsplit/Resources/en.lproj/Localizable.strings

@@ -3,3 +3,4 @@
 "contextMenu.tabColor" = "Tab Color";
 "contextMenu.clearColor" = "Clear Color";
 "contextMenu.chooseCustomColor" = "Choose Custom Color…";
+"tabBar.newTab" = "New Tab";

vendor/bonsplit/Sources/Bonsplit/Resources/ja.lproj/Localizable.strings

@@ -3,3 +3,4 @@
 "contextMenu.tabColor" = "タブの色";
 "contextMenu.clearColor" = "色をクリア";
 "contextMenu.chooseCustomColor" = "カスタムカラーを選択…";
+"tabBar.newTab" = "新規タブ";